The mean physical and optical properties of regional haze dominated by biomass burning aerosol measured from the C-130 aircraft during SAFARI 2000 Export

@article{haywoodJGR2003, abstract = {Instrumentation on the Met Office C-130 aircraft measured aerosol physical and optical properties during the Southern African Regional Science Initiative (SAFARI 2000) in September 2002 while flying from Windhoek, Namibia. Filter measurements of aged regional haze suggest a ratio of apparent elemental carbon (ECa) to organic carbon (OC) of 0.12 ± 0.02 and mass fractions of 5\% ECa, 25\% inorganic compounds, and 70\% organic matter (OC plus associated elements). The submicron size distribution of aged regional haze may be fitted with three lognormal distributions with geometric mean radii (rn) of 0.12 ± 0.01, 0.26 ± 0.01, and 0.80 ± 0.01 μm and geometric standard deviations (σ) of 1.3 ± 0.1, 1.5 ± 0.1, and 1.9 ± 0.4. Measurements over 2500 km from the emission region show similar rn and σ for the smallest two modes, while the third mode is absent presumably as a result of sedimentation. At a wavelength (λ) of 0.55 μm, effective medium approximations suggest a refractive index of 1.54 − 0.018i for aged regional haze aerosol. The single scattering albedo (ωoλ) derived using this refractive index and measured size distributions are consistent with those from the nephelometer and Particle Soot Absorption Photometer (PSAP). The optical parameters for aged regional haze a few days old are specific extinction coefficient (keλ=0.55) of 5.0 ± 0.8 m2 g−1, asymmetry factor (gλ=0.55) of 0.59 ± 0.02, and ωoλ=0.55 of 0.91 ± 0.04. Measurements of fresh biomass burning aerosol a few minutes old show smaller more absorbing particles. Vertical profiles of carbon monoxide, aerosol concentration, and aerosol scattering show a good correlation. Over land, aerosols become well mixed in the vertical from the surface to approximately 500 hPa. Over ocean, the aerosols can be separated from underlying stratocumulus cloud by a clear gap and a strong inversion, which may limit the indirect effect. }, author = {Haywood, Jim M. and Osborne, Simon R. and Francis, Pete N. and Keil, Andreas and Formenti, Paola and Andreae, Meinrat O. and Kaye, Paul H.}, citeulike-article-id = {4656297}, citeulike-linkout-0 = {http://www.agu.org/pubs/crossref/2003/2002JD002226.shtml}, citeulike-linkout-1 = {http://dx.doi.org/10.1029/2002JD002226}, day = {18}, doi = {10.1029/2002JD002226}, issn = {0148-0227}, journal = {Journal of Geophysical Research - Atmospheres}, keywords = {africa, airborne, safari, soot}, month = {February}, number = {D13}, pages = {8473+}, posted-at = {2009-05-28 08:01:03}, priority = {5}, title = {The mean physical and optical properties of regional haze dominated by biomass burning aerosol measured from the C-130 aircraft during SAFARI 2000}, url = {http://dx.doi.org/10.1029/2002JD002226}, volume = {108}, year = {2003} }

TY - JOUR ID - haywoodJGR2003 L3 - citeulike-article-id:4656297 N2 - Instrumentation on the Met Office C-130 aircraft measured aerosol physical and optical properties during the Southern African Regional Science Initiative (SAFARI 2000) in September 2002 while flying from Windhoek, Namibia. Filter measurements of aged regional haze suggest a ratio of apparent elemental carbon (ECa) to organic carbon (OC) of 0.12 ± 0.02 and mass fractions of 5% ECa, 25% inorganic compounds, and 70% organic matter (OC plus associated elements). The submicron size distribution of aged regional haze may be fitted with three lognormal distributions with geometric mean radii (rn) of 0.12 ± 0.01, 0.26 ± 0.01, and 0.80 ± 0.01 μm and geometric standard deviations (σ) of 1.3 ± 0.1, 1.5 ± 0.1, and 1.9 ± 0.4. Measurements over 2500 km from the emission region show similar rn and σ for the smallest two modes, while the third mode is absent presumably as a result of sedimentation. At a wavelength (λ) of 0.55 μm, effective medium approximations suggest a refractive index of 1.54 − 0.018i for aged regional haze aerosol. The single scattering albedo (ωoλ) derived using this refractive index and measured size distributions are consistent with those from the nephelometer and Particle Soot Absorption Photometer (PSAP). The optical parameters for aged regional haze a few days old are specific extinction coefficient (keλ=0.55) of 5.0 ± 0.8 m2 g−1, asymmetry factor (gλ=0.55) of 0.59 ± 0.02, and ωoλ=0.55 of 0.91 ± 0.04. Measurements of fresh biomass burning aerosol a few minutes old show smaller more absorbing particles. Vertical profiles of carbon monoxide, aerosol concentration, and aerosol scattering show a good correlation. Over land, aerosols become well mixed in the vertical from the surface to approximately 500 hPa. Over ocean, the aerosols can be separated from underlying stratocumulus cloud by a clear gap and a strong inversion, which may limit the indirect effect. IS - D13 JF - Journal of Geophysical Research - Atmospheres SN - 0148-0227 TI - The mean physical and optical properties of regional haze dominated by biomass burning aerosol measured from the C-130 aircraft during SAFARI 2000 VL - 108 SP - 8473 KW - africa KW - airborne KW - safari KW - soot AU - Haywood, Jim AU - Osborne, Simon AU - Francis, Pete AU - Keil, Andreas AU - Formenti, Paola AU - Andreae, Meinrat AU - Kaye, Paul PY - 2003/02/18/ UR - http://dx.doi.org/10.1029/2002JD002226 ER -